ZeroBehind

MariaDB replication, managed

A standby database that is zero transactions behind.

ZeroBehind sets up, monitors and switches MariaDB's built-in replication between two servers, even when one of them sits behind a home or office router. One agent per server. No cluster to learn.

Request early access See how it works

Runs on your own servers. Your data travels directly between them through an encrypted tunnel.

web-01 master, public IP
standby replica, behind NAT
0 transactions behind
Tunnel
encrypted, 17 ms
If the master fails now
nothing is lost
Status
In sync
Illustration of the pair view in the dashboard.
  • 3.5 splanned role switch, start to finish
  • < 0.5 spause seen by the application during the switch
  • 0acknowledged writes lost, in the planned switch and in the failover test
  • ~30 sto copy 1.2 GiB to a new replica over the internet

Measured in November 2026 on our own pair: a public server and a home server behind NAT, under continuous writes, verified row by row and by table checksums. Your numbers depend on your data and your link.

What you get

Replication you can actually operate

Works across NAT

The agents build their own encrypted WireGuard tunnel. The server behind the router calls out, so there is no port forwarding and no VPN to maintain.

A setup guide, not a manual

17 checks of your MariaDB configuration, with one-click fixes. Pair the servers with a one-time code, review the plan, start the copy.

The gap in transactions

The dashboard counts how many transactions the replica is missing, from GTID positions on both sides, and tells you what a failure right now would cost.

Switch roles on purpose

For maintenance or a move: the master pauses writes for a moment, the replica applies everything and takes over, and the old master follows it. Nothing is lost.

Take over after a failure

When the master is gone, the replica is promoted on your confirmation and says how many transactions may not have arrived. When the old master returns, it blocks its own writes.

One console for every pair

A web console and a signed, notarized macOS app show all your pairs at a glance. A single command gives monitoring an exit code. English, Polish and Italian.

How it works

From two servers to a working standby in three steps

  1. Install the agent on both servers

    One binary and a systemd service. It checks your MariaDB and proposes the settings replication needs.

  2. Pair them with a one-time code

    Each agent has its own certificate authority. Pairing pins the other side's identity, so nobody can sit in the middle.

  3. Start the copy and watch it catch up

    The replica receives a consistent snapshot and then follows the master with MariaDB's own GTID replication. Its previous data is kept aside, never deleted.

ZeroBehind does not replace MariaDB replication. It drives it: your data stays in standard MariaDB format on both servers.

Safety

Built by people who assume things will go wrong

Replication tools fail in the corners: a job that writes on the replica, an agent killed in the middle of a switch, a server that comes back after it was replaced. We test those corners on every release, on real MariaDB servers, under load.

And when ZeroBehind cannot be sure, it stops and tells you why. A short pause is better than two masters.

  • Never two masters. A replaced master blocks its own writes when it returns, and a restarted master holds writes until it has heard from its replica.
  • Nothing skipped silently. Transactions that exist on only one server are counted and shown. A rejoin that would lose them is refused.
  • Old data kept aside. Before a replica is replaced by a fresh copy, its data directory is moved, not removed.
  • Interrupted work is undone. If the agent dies during a copy, the server returns to the state it had before.
  • 8 role-switch scenarios and 7 interruption scenarios run against real servers before a version ships.

Questions

Good to know before you ask

Is this a database cluster?

No. It is one master and one replica using MariaDB's own asynchronous GTID replication, with the setup, monitoring and role switching done for you. If you need several writable nodes, you need a different tool.

Does my data pass through your servers?

No. The agents connect your two servers to each other directly, through an encrypted tunnel. The console talks to the agents the same way.

What does it run on?

We run and test it with MariaDB 10.11 and 11.8 on Ubuntu 24.04 and 26.04. Tell us what you use in the form below and we will say honestly whether it is covered.

Does it support MySQL?

Not yet. MariaDB comes first. If you run MySQL, say so in the form: it helps us decide what to build next.

Will my applications follow the new master automatically?

Not by themselves yet. After a role switch you point your applications to the new master. Automatic address handover is on the roadmap.

What does it cost?

Pricing will be published with the public release. Early-access users hear first.

Early access

Tell us about your servers

ZeroBehind is in early access. Leave your details and we will write back with access and, as soon as it is public, pricing.

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